Staphylococcus epidermidis: A differential trait of the fecal microbiota of breast-fed infants

Esther Jiménez,Natalia García,Juan M Rodríguez,Leonides Fernández,Rebeca Arroyo,Mar Albújar,Susana Delgado,Antonio Maldonado,Adolfo Gómez,Manel Jariod

doi:10.1186/1471-2180-8-143

Esther Jiménez, Natalia García + Show 8 more

Open Access

https://doi.org/10.1186/1471-2180-8-143

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Abstract

BackgroundBreast milk is an important source of staphylococci and other bacterial groups to the infant gut. The objective of this work was to analyse the bacterial diversity in feces of breast-fed infants and to compare it with that of formula-fed ones. A total of 23 women and their respective infants (16 breast-fed and 7 formula-fed) participated in the study. The 16 women and their infants provided a sample of breast milk and feces, respectively, at days 7, 14, and 35. The samples were plated onto different culture media. Staphylococcal and enterococcal isolates were submitted to genetic profiling and to a characterization scheme, including detection of potential virulence traits and sensitivity to antibiotics.ResultsThe feeding practice had a significant effect on bacterial counts. A total of 1,210 isolates (489 from milk, 531 from breast-fed and 190 from formula-fed infants) were identified. Staphylococcus epidermidis was the predominant species in milk and feces of breast-fed infants while it was less prevalent in those of formula fed-infants. Enterococcus faecalis was the second predominant bacterial species among the fecal samples provided by the breast-fed infants but it was also present in all the samples from the formula-fed ones. The biofilm-related icaD gene and the mecA gene were only detected in a low number of the S. epidermidis strains. Several enterococcal isolates were also characterized and none of them contained the cylA or the vanABDEG antibiotic-resistance genes. All were sensitive to vancomycin.ConclusionThe presence of S. epidermidis is a differential trait of the fecal microbiota of breast-fed infants. Globally, the staphyloccal isolates obtained from milk and feces of breast-fed infants contain a low number of virulence determinants and are sensitive to most of the antibiotics tested.

Highlights

Breast milk is an important source of staphylococci and other bacterial groups to the infant gut
Human milk is a major factor in the initiation and development of neonatal gut microbiota, because it contains prebiotic substances that promote the growth of selected bacterial groups in the infant gut [7], and because this substrate represents a continuous source of microorganisms to the infant gut during several weeks after birth [8,9]
Aerobic bacterial counts (9.25 and 9.54 log10 colony forming units (CFU)/g obtained in CNA and Violet Red Bile Agar (VRBA) media, respectively) were significantly lower than anaerobic bacterial counts (10.93 and 10.67 log10 CFU/g obtained in WCh and MRS media, respectively)

Summary

Introduction

Breast milk is an important source of staphylococci and other bacterial groups to the infant gut. Differences between breast-fed and formula-fed infants disappear rapidly and the gut ecosystem evolves into a stable host-specific community predominated by obligate anaerobes [1]. Human milk is a major factor in the initiation and development of neonatal gut microbiota, because it contains prebiotic substances that promote the growth of selected bacterial groups in the infant gut [7], and because this substrate represents a continuous source of microorganisms to the infant gut during several weeks after birth [8,9]. The presence of a few predominant bacterial species in breast milk [10] may explain why gut microbiota of breast-fed infants is composed of a narrow spectrum of species, and a more diverse microbiota develops only after weaning

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